During a combustion cycle of an internal combustion engine (ICE), air/fuel mixtures are provided in cylinders of the ICE. The air/fuel mixtures are compressed and combusted to provide output torque. After combustion, pistons of the ICE force exhaust gases in the cylinders out through exhaust valve openings and into an exhaust system. The exhaust gases may contain nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (HCs). An exhaust gas treatment system of the ICE may include one or more selective catalytic reduction (SCR) catalysts to reduce exhaust emissions. The SCR catalysts can be used to reduce NOx in the exhaust system. Specifically, an SCR catalyst converts NOx into nitrogen N2 and water (H2O).